Influence of magnetorheological elastomer on tool vibration and cutting performance during boring of hardened AISI4340 steel

During boring process, tool vibration is a major concern due to its overhanging length, which results in high cutting force, poor surface finish, and increase in tool wear. To suppress tool vibration and improve cutting performance, a novel technique in rheological fluid was designed and developed. In this work, a magnetorheological elastomer (MRE) was developed, and parameters, such as piston location, current intensity, and coil winding direction, were considered. Cutting experiments were conducted to obtain a set of parameters that can efficiently control vibration during boring of hardened AISI 4340 steel. Taguchi method was used to optimize the cutting condition, and findings show that the cutting tool embedded with the MRE reduced tool vibration and effectively increased cutting performance.

     

Constitutive Modeling of a Schistose Rock in the Himalaya

Strain‐controlled triaxial tests have been conducted using servo‐controlled loading system on three schistose rocks from a hydropower project in the Himalaya. A constitutive model based on the disturbed state concept is used to model the behavior of the rocks. Predictions are made using a single point method and finite element method. The constitutive model is found to provide satisfactory predictions. The DSC model is used to predict observed behavior of a powerhouse cavern; the relevant paper, “Analysis of a Powerhouse Cavern in the Himalaya,” appears in this issue.     

Analysis of Drying Kinetics of Iron Ores using Irreversible Thermodynamics and Transport Phenomena Principles

Drying kinetics of iron ores, the primary raw material for the iron and the steel industry, has been studied in this work. Experimental drying kinetics and equilibrium moisture content data have been obtained using thermogravimetric techniques at controlled conditions of humidity, temperature and gas flow. A theoretical model based on the principles of irreversible thermodynamics and transport phenomena, and a computer program for the simulation of drying process has been developed (SimDry 1.0 for Windows). The results of simulation have been compared with the experimental results and there has been reasonable agreement between them.     

Zur Struktur geschmolzener CaO-SiO2-Al2O3-Schlacken

Methode zur Berechnung mittlerer molarer Massen von ringförmigen Anionenkomplexen in CaO-SiO₂-Al₂O₃-Schlacken. Annahme von dreifacher oder vierfacher Koordination für Aluminium. Korrelierung von Schrifttumswerten der Viskosität mit berechneten Anionenmassen.     

Robust underwater obstacle detection and collision avoidance

A robust obstacle detection and avoidance system is essential for long term autonomy of autonomous underwater vehicles (AUVs). Forward looking sonars are usually used to detect and localize obstacles. However, high amounts of background noise and clutter present in underwater environments makes it difficult to detect obstacles reliably. Moreover, lack of GPS signals in underwater environments leads to poor localization of the AUV. This translates to uncertainty in the position of the obstacle relative to a global frame of reference. We propose an obstacle detection and avoidance algorithm for AUVs which differs from existing techniques in two aspects. First, we use a local occupancy grid that is attached to the body frame of the AUV, and not to the global frame in order to localize the obstacle accurately with respect to the AUV alone. Second, our technique adopts a probabilistic framework which makes use of probabilities of detection and false alarm to deal with the high amounts of noise and clutter present in the sonar data. This local probabilistic occupancy grid is used to extract potential obstacles which are then sent to the command and control (C2) system of the AUV. The C2 system checks for possible collision and carries out an evasive maneuver accordingly. Experiments are carried out to show the viability of the proposed algorithm.     

Admission control by implicit signaling in support of voice over IP over ADSL

Voice over DSL (VoDSL) is a technology that enables the transport of data and multiple voice calls over a single copper-pair. Voice over ATM (VoATM) and Voice over IP (VoIP) are the two main alternatives for carrying voice over DSL. ATM is currently the preferred technology, since it offers the advantage of ATM’s built-in Quality of Service (QoS) mechanisms. IP QoS mechanisms have been maturing only in recent years. However, if VoIP can achieve comparable performance to that of VoATM in the access networks, it would facilitate end-to-end IP telephony and could result in major cost savings. In this paper, we propose a VoIP-based VoDSL architecture that provides QoS guarantees comparable to those offered by ATM in the DSL access network. Our QoS architecture supports Premium and Regular service categories for voice traffic and the Best-Effort service category for data traffic. The Weighted Fair Queuing algorithm is used to schedule voice and data packets for transmission over the bottleneck link. Fragmentation of large data packets reduces the waiting time for voice packets in the link. We also propose a new admission control mechanism called Admission Control by Implicit Signaling. This mechanism takes advantage of application layer signaling by mapping it to the IP header. We evaluate the performance of our QoS architecture by means of a simulation study. Our results show that our VoIP architecture can provide QoS comparable to that provided by the VoATM architecture.     

Wind Response Control of Building with Variable Stiffness Tuned Mass Damper Using Empirical Mode Decomposition/Hilbert Transform

The effectiveness of a novel semiactive variable stiffness-tuned mass damper (SAIVS-TMD) for the response control of a wind-excited tall benchmark building is investigated in this study. The benchmark building considered is a proposed 76-story concrete office tower in Melbourne, Australia. It is a slender building 306 m tall with a height to width ratio of 7.3; hence, it is wind sensitive. Across wind load data from wind tunnel tests are used in the present study. The objective of this study is to evaluate the new SAIVS-TMD system, that has the distinct advantage of continuously retuning its frequency due to real time control and is robust to changes in building stiffness and damping. In comparison, the passive tuned mass damper (TMD) can only be tuned to a fixed frequency. A time varying analytical model of the tall building with the SAIVS-TMD is developed. The frequency tuning of the SAIVS-TMD is achieved based on empirical mode decomposition and Hilbert transform instantaneous frequency algorithm developed by the writers. It is shown that the SAIVS-TMD can reduce the structural response substantially, when compared to the uncontrolled case, and it can reduce the response further when compared to the case with TMD. Additionally, it is shown the SAIVS-TMD reduces response even when the building stiffness changes by ±15% and is robust; whereas, the TMD loses its effectiveness under such building stiffness variations. It is also shown that SAIVS-TMD can reduce the response similar to an active TMD; however, with an order of magnitude less power consumption.     

Development of High Performance Steel Products in Sail Through R&D Initiatives

Steel Authority of India Limited (SAIL), through its Corporate R&D i.e. RDCIS, has been working incessantly for the development of new steel products with superior quality attributes to meet the requirements of Indian market. The product development activities have always been supported by in-house/collaborative research work which has led to deeper understanding on the process know-how, resulting in launching of cost-effective products in Indian market. Some of the products developed by SAIL in the flat product category include high strength thin gauge HR coil for automobile sectors, SAILMA 550 HI/SAILMA 600 grade plates for penstocks and earthmovers, SAIL HITEN 690 AR plates for automated teller machines chest, high strength plates with guaranteed through thickness ductility for railways and Defence sectors, boiler quality plates (ASTM 387 Gr. 12) for power sector, API X 70 grade HR coils and plates for Linepipe application. In the long products category, EQR TMT rebar, Roof/Rock Bolt (Fe—600) TMT rebars for mines and tunnels, corrosion resistant TMT rebars for construction sector, Al-killed low carbon CC blooms for cold reducers, Al-killed medium carbon CC blooms for forging have been developed recently through R&D initiatives in SAIL. This paper describes some of the products which were recently developed in SAIL.